When pipelines, especially pipelines made of plastic, are laid and then covered with dirt or concrete there is the uncertainty that the completed pipeline may or may not have been completely or partially collapsed by external forces, or by the weight of the earth or concrete placed atop it. The pipe is not available for external examination because it is covered, and it is therefore necessary to run a gauge through it.
Go/no go pipe deflection gauges are known. In one form it is simply a ball which is pulled through the pipe. Another known gauge is a cage-like rod arrangement which is supported by plate-like means which substantially occludes the cross-section of the pipe. Yet another known construction involves an axial outer boundary having such a long length that the gauge cannot pass through a bend without destroying the gauge or the pipe. Gauges which substantially occlude the cross-section of the pipe are drawn through with great difficulty and sometimes cannot be drawn through at all for the reason that when the pipes are laid it is not uncommon for all kinds of debris to find their way into the pipe. The gauge will be brought to a stop by debris jammed between it and the wall of the pipe. Extra-long gauges have a tendency to jam, or to cut and destroy the pipe when pulled too hard when they encounter a bend. In all such vents, it is not possible to determine whether the pipe has collapsed, or whether some problem is created by the gauge itself.
It is an object of this invention to provide a go/no go pipe deflection gauge which can readily be pulled through a pipe without jamming against debris, which can pass through turns, and can do these things without cutting the walls, while accurately and correctly determining whether the pipe has been deflected or not.
A go/no go pipe deflection gauge according to this invention includes a central spindle which has an axis of length and a pair of ends. Cable attachment means is provided on both of these ends to which a cable can be attached for pulling the gauge through a pipe and for pulling it back out of the pipe if it becomes jammed or if the pipe has deflected. A plurality of vanes extends radially from the spindle. They are angularly spaced from one another, and are parallel to the axis. Each of them has an outer boundary which includes a central substantially straight segment parallel to the axis, and a pair of end segments which extend from respective ends of the central segment toward the axis.
According to a preferred but optional feature of the invention, there are at least nine of said vanes.
According to still other preferred but optional features of the invention, the vanes are flat, stiff, and resistant to bending, and the end segments are straight and form obtuse angles with the central section.
According to yet another preferred but optional feature of the invention, the vanes can be seated and held in slots in the spindle by means such as end caps, whereby the vanes can readily be changed so that with a single spindle, gauges of various diameters can be assembled by substituting vanes of appropriate dimensions.